Following the Nov. 3 election and subsequent recounts in some states, as well as unsuccessful court challenges, the outcome is clear, they wrote, while not specifying Trump in the article.
The former Pentagon chiefs warned against use of the military in any effort to change the outcome.
“Efforts to involve the U.S. armed forces in resolving election disputes would take us into dangerous, unlawful and unconstitutional territory,” they wrote.
Biden has complained of efforts by Trump-appointed Pentagon officials to obstruct the transition.
In reversing himself, Miller cited “recent threats issued by Iranian leaders against President Trump and other U.S. government officials.” He did not elaborate, and the Pentagon did not respond to questions.